When I hear the sort of thing you would call "applause lights", I don't always think of that as an obvious fact that everyone in their right mind would agree on. Rather, I get the impression the speaker is implying that someone they strongly disagree with does believe this obvious fact is not true, or that this ridiculous notion is.

If for example I hear someone say "we shouldn't be hugging criminals, we should be locking them up", I interpret that as a very one-sided opposition to a grossly misrepresented opponent who goes a bit easier on convicts. Of course this person wouldn't literally believe the reverse that "we should be hugging criminals instead of locking them up", but she might believe something that a bigot could paraphrase as such with a straight face.

I think this is also the reason why the speaker's supporters applaud to statements like that - it implies the issue is very simple and clear-cut, only one side (ours) is remotely sensible, and you'd have to be insane to disagree. One-sidedness feels good. Very blatant one-sidedness feels even better.